1. Field of the Invention
The present invention relates to a process cartridge having a plurality of developing units and also to an image forming apparatus on which the process cartridge is mountable.
The term "image forming apparatus" in this specification is used to mean various types of apparatuses and machines such as electrophotographic copying machines, printers including laser beam printers, facsimile machines, and so forth. Although a process cartridge and a multi-color image forming apparatus are specifically mentioned in the following description, it is to be understood that such devices are only illustrative and the present invention may generally apply to a variety of types of process cartridges having a plurality of developing units and image forming apparatuses which operate in cooperation with such process cartridges.
2. Description of the Related Art
Process cartridges for use in multi-color image forming apparatuses have been known.
In general, such a process cartridge has an image carrier and a plurality of developing units which act on the image carrier, as disclosed, for example, in U.S. Pat. No. 4,500,195. The process cartridge, as well as the multi-color image forming apparatus which forms multi-color images by using such a process cartridge, is essentially required to have a construction which enables the developing units to operate correctly without impairing the ease of mounting and demounting of the process cartridge on and from the apparatus.